Signal control apparatus



Nov. 7, l944 A. E. DoDD 2,362,194

SIGNAL CONTROL APPARATUS Filed July 30, 1942 2 Sheets-Sheet l Llql H 4 I@ 57 21%15 \A 2? 3%?? FA -I)IZ LZ LZ HZsTTaR/WK Nov. 7, 1944. A. a ,Dono

SIGNAL CONTROL APPARATUS Filed July 30, 1942 2 Sheets-Sheet 2 LZ LLZ .5 S2

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a. y. wm M N. M E n W14 @am Mw Patented Nov. 7, 1944 SIGNAL CONTROL APPARATUS Arthur E. Dodd, Edgewood, Pa., assigner to The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania Appueation July so, 1942, serial No. 452,904

6 Claims.

,n My invention rrelates to signal control apparatus, and particularly to apparatus for flashing danger signals at highway-railroad crossings to warn users of the highway of the approach of a train upon the railway. y

In many installations of highway crossing signals employing flashing lights,.thelamps are energized by alternating current except when a failure in the alternating current supply occurs, in which event the lamps are connected to a source of direct current,fsuch as astorage battery, through the medium of a power transfer relay. .The relays employed for flashing the lights in such installations are usually of the direct current type, and are therefore normally energized from the storage battery which serves as the standby s ourceof power for thel lights.

If the flasher relays in such installations can be made to operate from either alternating or direct current, a savings can be effected in the relay contacts required, and the wiring can be simplied, and one object of my present invention is to provide means for accomplishing this desirable result.

Another object of .my invention is to provide means whereby a flasher relay can be made to operate on either alternating ordirect current .without changing the physical construction of the relay.

The flasher relays commonly employed for flashing lights in control apparatus embodying my inventiony normally include a pair of windings and an armature which is caused to oscillate by alternately short circuiting the relay windings by contacts operated by said armature, and according to my invention I accomplish the aforementioned objects by interposing in the control circuit for the flasher relay between the control contacts and each winding one or more rectiers so arranged that the windings will always be supplied with direct current of the same polarity regardless of whether the control circuit is energized from a source of direct or alternating current. Since the current which flows through the control contact with this arrangement is normally alternating current, this contact may be utilized to perform the added function of flashing the lights of a highway crossing signal, with the result that for the same total number of relay contacts, the lamp capacity of `the flasher relay will beincreased or for a given lamp capacity one set of contacts can be` eliminated. This arrangement also has the advantage vthat it is only necessary to run two control wires from the poWersource tothe flasher relay instead of the four wires that have heretofore usually been required, which results in a reduction in the number of contacts required on the relays normally employed to control the control circuits.

I shall describe three forms of signal control apparatus embodying my invention, and shall then point out the novel features thereof in claims.

In the accompanying drawings, Fig. 1 is a diagrammatic View showing one form of signal control apparatus embodying my invention. Figs. 2 and 3 are diagrammatic Views showing modified forms of theapparatus illustrated in Fig. 1, and also embodying my invention.

Similar reference characters refer to similar parts in all three views.

Referring rst to Fig. 1, the reference characters I and la designate the track rails of a stretch of railway track over which trafllc normally moves in both directions, and which stretch is nteisectedfby a highway H,` The track rails l and la are divided by means of insulated joints 2 to form two track sections A-B and B-C which extend in opposite directions from the highway, The one trackv section A-B is provided with a track circuit comprising a track battery 3 connected across the rails at one end of the' section and the one magnet 4 of an interlocking relay IR connected across the rails at the other end ofthe section, while the other track section B-C is provided with a similar track circuit comprising a track battery 3 connected across the rails at one end of the section, and the other magnet 5 of the interlocking relay IR connected across the rails at the opposite end of the section.

The interlocking relay IR may be of any of the well-known types, such for example, as the relay described and claimed in Letters Patent of the United States No. 1,799,629, granted to William K. Lockhart and Thomas J. OMeara on April 7,

1931, and as here shown is provided with a back contact 6 which is controlled by magnet 4 and .with a back contact 1 which is controlled by magdeenergized, even though the first magnet to become deenergized subsequently picks up.

It will be seen, therefore, that when a train moving from left to right traverses the stretch of track shown in the drawings, contact 6 of relay IR will become closed upon the entrance of the train into section A-B and will subsequently remain closed until the train clears this section, but that under these conditions contact 'I will remain open even though magnet will become deenergized while the train is traversing section B-C. In a similar manner, when a train traverses the stretch of track shown in the drawings in the opposite direction, contact 'l will become closed vwhen the train enters section B-C and will subsequently remain closed until the train clears this section, but contact 6 will remain open in spite of the fact that magnet 4 will become deenergized while the train is passing through section A-B.

Located on opposite sides of the railway adjacent the intersection of the railway and the highway are two highway crossing signals SI and S2 the function of which is to warn users of the highway when a train is approaching the highway in either direction. These signals as here shown are of the well-known type comprising two lamps which are adapted to be alternately flashed to simulate the effect of a swinging red lantern, the lamps o the signal SI being designated by the reference characters LI and LLI, and the lamps of the signal S2 being designated by the reference characters L2 and LL2.

For the purpose of flashing the lamps when a train is approaching the intersection a flasher relay FR controlled by the interlocking relay IR is provided. This relay is of well-known construction and comprises three magnetizable cores 8, 9 and I@ connected together at their upper ends by a backstrap I I and provided at their lower ends with enlarged pole pieces 8a, 9a and Illa, respectively. The core 8 carries an energizing winding l2 and the core I8- carries a similar energizing winding I3, while the core 9 carries a plurality of closed conductors here shown as washers I4, the number of which serves to determine the time characteristics of the relay, as will be explained more fully hereinafter.

A magnetizable armature I5 is pivotally supported directly below the pole piece 8a for swinging movement toward one or the other of the pole pieces 8d and Ia, and is operatively connected with two contact fingers IB and II. When armature I5 is swung toward pole piece Illa, as shown in the drawings, contact nger I6 engages a fixed contact member 16a to close a contact IE-IGa and contact finger I1 engages a fixed contact member IIa to close a contact I'I-I'I'a. When armature I5 is swung toward pole piece 8a, however, contact finger I6 then engages a fixed contact member IGZ) to close a contact IE-I6b and contact finger IT engages a fixed contact member Ib to close a contact I'I--I 1b.

In accordance with my present invention the windings I2 and I3 are connected in series in an energizing circuit which includes two full wave rectiers, one of which RI has its output terminals connected directly with winding I2 and the other of which R2 has its output terminals connected directly with winding I3. This circuit also includes a pair of wires I8 and I9 and the two contacts 6 and I of interlocking relay IR in multiple, and is arranged to be supplied with alternating current from the secondary winding 20 of a transformer T, or with direct current from a battery D, according as the front contacts 2 I -2 I a and 22-22a or the back contacts 2I-2Ib and 22-22b of a power transfer relay PTR are closed. The primary winding 23 of transformer T is constantly connected with the terminals BX and CX of a suitable source of alternating current not shown, and the power transfer relay PTR is constantly connected to the secondary winding 20 of transformer T. It follows,.therefore, that the energizing circuit for the windings I2 and I3 of relay FR will be supplied with alternating current from the secondary winding 20 of transformer 'I' except in the event of failure in the alternating current supply in which case the resultant deenergization of relay PTR will cause this circuit to be supplied with direct current from the battery D. The battery D is preferably of the storage type, and is maintained in its fully energized condition under normal conditions by energy supplied to it from a second secondary winding 24 of transformer T through a rectifier R3.

The energizing circuit for the windings I2 and I3 of relay FR further includes the contacts I6-I6a and l6-I6b of relay FR so arranged that when the contact I6-I6a is closed, it will short circuit the input terminalsof rectifier R2, and that, when the contact IB-Ib is closed, it will short lcircuit the input terminals of rectifier RI. The terminals of the windings I2 and I3 are connected with the output terminals of the rectiiers RI and R2 in such manner that the ux induced in core 9 when the winding I2 is energized will traverse this core in the opposite direction to that induced in core 9 when the winding I3 is energized.

With the energizing circuit for relay FR arranged in the` manner just described, when this circuit becomes closed ateither contact Bor contact 'I of relay IR, if armature I5 occupies the position shown so that contact I6-I6a is closed, current will be supplied. to winding I2 through this contact, but winding I3 will remain deenergized due to the short circuit provided by this contact. The energization of winding I2 will set up a flux in core 8 which will cause armature I5- to swing toward pole piece 8a. This motion of the armature will open contacts I6-I6a and I'I-I'Ia and close contacts IB--I6b and II-Ilb. The closing of contact IB-ISbA will short circuit winding I2, and the eld set up in core 8 by this winding will commence to decay.. Due, howeveri to the snuhbingr effect. of the short circuited winding and to the,y washers I4 ony core 9, this decay will be comparatively. slow. The opening of contact l6--I6a in thev meantime will have removed the short. circuitfrom winding I3 with the result. that current will now, be supplied to winding I2 through contact II--Ilm The growth of the field set up in core Ill by. this latter winding will be comparatively slow due. to. the washers I4, but after an. interval of time. the. torque exerted on armature. I5 by this flux will overbalance the torque. exerted .on armature. I5 by the decaying flux in core..8, and when this happens, armature I5 will swing toward pole piece lIML This motion will rst open contacts VIS--Iib and Il lflb and will then close contacts I6-I6a and I'I-I'Ia. The. eld of winding I2 will' then slowly build up andthefield. of winding I3 will slowly decay, this decaybeing retarded bythe self-inductancel of winding lit andv the washers I4. Eventually the torque.l exerted by theA flux in core I0: will not be. sufiicientto hold armature I5 and the armaturewill thenagain swing to ward pole piece 3a. It will therefore be ap parent` that armature I5.` will beswung to. and

l from or oscillated as long as either contact 6 or contact I of interlocking relay IR remains closed, and it will also be apparent that a time interval will elapse between successive armature movements. It will further be apparent that since thev flux set up by both windings I2 and I3 traverses the common core 9, and since the rate at which the ux builds up and decays in this core depends upon the number of washers I4 on this core, the time interval which elapses between successive armature movements may be readily varied by varying the number of washers I4 on core 8. The operation of relay FR will be the same regardless of whether the energizing circuit is supplied with alternating current from the secondary winding 20 of transformer T 0r with direct current from the battery D.

The lamps LI and LLI of signal SI are connected in series between'the line wires I8 and I9, but when the contact II-Ia is closed, the lamp LLI is short circuited by this contact and when the Contact I6-I6b is closed, the lamp LI is short circuited by this contact. parent, therefore, that when the relay FR is operating, the lamps LI and LLI will be alternately flashed, and that if the relay should fail to operate for any reason, one or the other of these lamps will always be lighted. f

In a similar manner the lamps L2 and LL2 of signal S2 are connected in series between the line wires I8 and I9, but when the contact I'I-IIa is closed, the lamp LL2 is short circuited by this contact, and when the contact I'l-I'Ib is closed, the lamp L2 is short circuited by this contact.v It follows, therefore, that when relay FR f is operating, these lamps will be flashed in unison with the lamps LI and LLI, and that if relay FR fails to operate for any reason when its energizing circuit becomes closed, one or the other of the lamps L2 and LL2 will always be lighted.

The operation of the apparatus as a whole will be apparent from an inspection of the drawings and from the foregoing description without further detailed description.

As was pointed out hereinbefore, it is desirable in the interest of economy to normally energize the lamps of highway crossing signals by alternating current since it can be obtained at a lower cost than direct current, and it should be particularly pointed out that with the apparatus arranged in the manner just described I am able to accomplish this result and to control the flashing of the lights with a standard direct current flasher relay over a single pair of wires extending from the source of power to the relay location. This effects a savings of at least two wires over the arrangements heretofore generally employed in which the relay is normally energized from direct current and the lamps from alternating current.

It should also be pointed out that since the rectifiers R2 and RI are located between the control contacts Ili--Ila and IB-IIb and the associated windings I2 and I3 of relay FR, I am ableto utilize the contacts I6-I6a and I6-I6b to perform the added function of flashing one l or more pairs of lights with the result that for the same total number of relay contacts, the lamp capacity of the flasher relay is increased, or for a given lamp capacity one set of lamp contacts can be eliminated.

Referring now to Fig. 2, as here illustrated, the full wave rectifier RI shown associated with the winding I2 in Fig. 1 has been replaced by two half wave rectiers R4 and R5, and the full It will be aphalf wave rectiers R6 and RI.

wave rectifier R2 shown associated with the winding I3 in Fig. 1 has been replaced by two The half wave rectifiers R5 and RI are connected in the energizing circuit vin series with the windings I2 and I3, respectively, and serve to supply these windings with half wave energy of the proper polarity when the energizing circuit is being supplied with alternating current, While the rectiers R4 and R6 are shunted across the windings I2 and' I3 and'help to smooth out the pulsations in the half wave energy supplied to these windings through the rectifers R5 and R'I.

This arrangement has the advantage that it reduces the number of rectifier units required, but it is open to the disadvantage that the relay windings I2 and I3 are required to have a lower resistance than is the case when the full wave rectiers RI and R2 are employed. It is also subject to the disadvantage that it is necessary in order to cause the relay FR to operate in the event of failure in the alternating current supply that the battery D be connected with the energizing circuit in a manner to cause the wires I8 and I9 to have a particular relative polarity.

It should be pointed out that it is at present the common practice to shunt a half wave rectifier across the windings I2 and I3 for the purpose of suppressing radio interference, and when this is the case, the only additional rectifiers required with the arrangement shown in Fig. 2 are the rectiiiers R5 and R'I.

The operation of the apparatus as a whole when arranged as shown in Fig. 2 is similar to the operation of the apparatus when arrangedl as shown in Fig. 1, and will be apparent from an inspection of the drawings without further detailed description.

Referring now to Fig. 3, as here shown, the windings I2 and I3. are center tapped, and have their center taps connected with the line wires I9 and I8, respectively. Two half wave rectifiers R8 and R9 connected in series and poled in the same direction insofar as their series con- I nection is concerned are shunted across the winding I2 and have their common connection connected to the contact-finger I 6, and two similar half wave rectifiers RI U and RI I connected in series and poled in the same direction insofar as their series connection is concerned'are shunt-` ed across the winding I3 and have their common connection connected to the contact finger I6. The windings I2 and I3 are so constructed that each half of these windings has the same resistance as the total resistance of these windings in Figs. 2 and 3. The remainder of the apparatus shown in Fig. 3 is similar to the corresponding portion of the apparatus shown in Figs. 1 and 2.

With the apparatus arranged as rshown in Fig. 3, when the energizing circuit is supplied with alternating current, the windings I2 and I3 will become alternately short circuited to cause the relay to oscillate in the same manner as in the preceding views. When either winding is not short circuited, the two halves of the winding will be alternately energized on alternate half cycles of the alternating current and the associated rectifiers are so poled that the ilux set up in the associated core when either half is energized will traverse-the core in the same direction, whereby the core will be supplied with energy on each half of the alternating current cycle, thereby accomplishing full wave rectification with fewer rectifier units than in Fig. 1.

With this arrangement it isnot necessary that the wires i8 and I9 have a particular relative polarity.y when the energizing circuit is supplied with directy current, and the cores will be supplied with flux of substantially the same magnitude regardless of whether the energizing circuit is supplied with alternating or direct current.

Although I have herein shown and described only three forms of signal control apparatus embodying my invention, it is understood that various changes and modiiications may be'made thereinwithin the scope of the appended claims without departing from the spirit and scope of my inventionA Having thus described my invention, what I clairnis:

1. In combination, a relay comprising two windings, an armature which is moved to one position or another according as one winding or the other is energized, a first Contact closed when said armature occupies its one position and a second contact closed when said armature occupies its other position, a rst full wave recti- :der having its output terminals connected with said one winding, a second full wave rectiiier having its output terminals connected with said other winding, an energizing circuit for said relay including a pair of wires one of which is connected with the one input terminal of the one rectifier and the other of which is connected with the one input terminal of the other rectier, means connecting theV remaining input terminals of said rectiers together, means for short circuiting said one Winding when said rst contact is closed, and means for short circuiting said other winding when said other contact is closed, whereby said armature will oscillate when said energizing circuit is supplied with either alternating or direct current.

2. In combination, a relay comprising two windings, an rmature which is moved tov-one position or another according as one winding or the; other is energized,- an energizing circuit for said windings including said windings connectedin series, means including a first contact closed when said armature is moved to said one position for short circuiting said one winding, means.

including a second contact closed when said armature is moved to said other position,r for short circuiting said other winding, and two ull` wave rectiers one interposed in said circuit between each winding and each contact and each having its output terminalsconnected with the terminals of the associated 'winding andits, in

pnt terminals connected across the associated contact in such nia-nner that the rectifier will be short circuited when the associated contact is closed, whereby said windings will be supplied with direct current of thevsame polarity regardless of whether said energizing circuitl is supplied with direct or'alternating current.

3. In combination, a relay comprising windings, an armature which is moved to'one position or another according as one winding or the other is energized, two contacts controlled by saidV armature and one closed when said armature is moved to said o -e position and the other closed when said armature is moved to said other position, circuitfrneans for short circuiting` said one winding over said .one contact'and for supplying said other winding with current' over two CII

said-one contact whensaid one contact is closed other circuit means for short circuiting said other winding over said other contact and for supplying saidV one winding with current over said other contact when said other contact is closed; andl rectier means included in said circuit means between said windingsfand said con tacts to'render said relay capable of operation oneither direct or alternating current.

4. In combination, arelay comprising two windings, an armature which is moved to one position-cr another according as one winding or the other isenergized, two contacts controlled by said armature and one closed when said armaturev is moved to said one position and the other closed' when said armature is moved to said other position, circuit means for short circuiting said one winding over said one contact and for supplying at least a part of said other winding with current over said one contact when said one contact is closed, other circuit means for short circniting said other winding over said other contactY and for supplying at least a part of said one winding with current over said other contact when said other contact is closed, and rectier'means associated with each winding to render-said relay capable of operation on either direct or alternating current.

5. In combination, a relay comprising two windings, an armature which is moved to one position or another according as one winding or the. other is energized, two contacts controlled by said armature and one closed when said armature isl moved to said one positionland the other closed when said armature is moved to saidy other position, circuit means for short cir-l cuit-ing said one winding over said one contact and forsupplying said other winding with current over said one contact when said one contact is closed, other circuit means for short circuiting said other winding over said other contact and for supplying said one winding with current over said other contact when said other contact, is closed, two half wave rectifiers one included in each said circuit means between each winding and the Contact over which the respective winding isenergized, and two other half wave rectiers one` shunted across each winding, said last two mentioned rectifiers each being oppositely poled with respect to the other rectifier associatedwith the same winding.

6. In combination, a relay comprising two center tapped windings, an armature which is` moved tovone position or another accordingas one winding or the other is energized, two contaetscontrolled by said armature and one closed when said armature is moved to said one position and the other closedwhen said armature 's moved to said other position, two half Wave rectiers connected in series across one winding, two other half wave rectiers connected in series acr ss the other winding, a pair of wires connected respectively with the center taps of said windings; said wires being at times supplied with alternating current and at other times with directl current, a third wire connecting the common connections of said half Wave rectifier together, and means connecting said one contact between said' third wire. and the one circuit wire and saidother contact' between said'third wire and the other circuitwire.

ARTHUR. E. D ODD, 

